nodeview: only remove dragged edge if arrow was dragged

app/widget/nodeview/nodeview.cpp

@@ -566,7 +566,9 @@ void NodeView::mouseReleaseEvent(QMouseEvent *event)
     MultiUndoCommand* command = new MultiUndoCommand();
 
     if (create_edge_already_exists_) {
-      command->add_child(new NodeEdgeRemoveCommand(create_edge_->output(), create_edge_->input()));
+      if (!create_edge_->IsConnected()) {
+        command->add_child(new NodeEdgeRemoveCommand(create_edge_->output(), create_edge_->input()));
+      }
     } else {
       delete create_edge_;
     }

app/widget/nodeview/nodeviewedge.h

@@ -89,6 +89,11 @@ public:
    */
   void SetConnected(bool c);
 
+  bool IsConnected() const
+  {
+    return connected_;
+  }
+
   /**
    * @brief Set highlighted state
    *